F-35B

[CAPFlyer]

The limitation on the Harrier's operations when performing VTOL operations was due to the need to use demineralized water injection to help cool the engine intake air during vertical flight. There is only enough of it onboard for approx. 90 seconds of flight, so that is what causes the limit and the "black" exhaust when in hover. With the F-35B, the only theoretical limit would be on if there were bearing temperatures to care for and fuel. There is no need to augment the intake air as was stated previously. This is why the lift fan design is much preferred but was never really feasible due to performance loss in the engines to drive the lift fan and the problems with part tolerance control for reasonable cost. With modern capabilities in CNC machining and even 3D metal printing, many of these issues have been resolved allowing for an acceptable performance loss and reliable operations of the drive train.

Testing will bear out how rugged the system is, but from the initial testing series, it seems to be holding up well as they are conducting vertical and STOVL operations on a regular basis, meaning little work is being needed between flights to "fix" any issues.

Ya mean like early versions of the R/R RB-211 on L-1011's?

Umm, the only problem the RB211 had in development was that the original composite fan blades weren't up to snuff and the titanium blades had problems too with their metallurgy. The fans themselves were fine.

[TXCOMT]

The best place to find out stuff on the F-35 that is in the public domain, is to read the forum section on the F-35 over on F-16.net.

Maybe, but I usually ask the two F-35 engineers who live across the street! Gotta love living in Fort Worth!

TXCOMT

[Noha307]

The limitation on the Harrier's operations when performing VTOL operations was due to the need to use demineralized water injection to help cool the engine intake air during vertical flight. There is only enough of it onboard for approx. 90 seconds of flight, so that is what causes the limit and the "black" exhaust when in hover. With the F-35B, the only theoretical limit would be on if there were bearing temperatures to care for and fuel. There is no need to augment the intake air as was stated previously. This is why the lift fan design is much preferred but was never really feasible due to performance loss in the engines to drive the lift fan and the problems with part tolerance control for reasonable cost.

Never knew that, thanks for the info. I was trying to figure out why there was such a limitation on vertical flight for the Harrier, and based on my [incorrect] understanding that it was a fuel quantity issue, I was left wondering how, if they used up so much fuel hovering, they had enough to do anything else.

[The Inspector]

The limitation on the Harrier's operations when performing VTOL operations was due to the need to use demineralized water injection to help cool the engine intake air during vertical flight. There is only enough of it onboard for approx. 90 seconds of flight, so that is what causes the limit and the "black" exhaust when in hover. With the F-35B, the only theoretical limit would be on if there were bearing temperatures to care for and fuel. There is no need to augment the intake air as was stated previously. This is why the lift fan design is much preferred but was never really feasible due to performance loss in the engines to drive the lift fan and the problems with part tolerance control for reasonable cost. With modern capabilities in CNC machining and even 3D metal printing, many of these issues have been resolved allowing for an acceptable performance loss and reliable operations of the drive train.

Testing will bear out how rugged the system is, but from the initial testing series, it seems to be holding up well as they are conducting vertical and STOVL operations on a regular basis, meaning little work is being needed between flights to "fix" any issues.

Ya mean like early versions of the R/R RB-211 on L-1011's?

Umm, the only problem the RB211 had in development was that the original composite fan blades weren't up to snuff and the titanium blades had problems too with their metallurgy. The fans themselves were fine.

Would that include the TWA bird that spit the inlet fan out of #3 over the Midwest when the hub failed?
I spent a lot of time trying to get the LUCAS engine controllers to 'wake up' so the friggin' engine would start after a long mod or big 'D' check on AMWest and other RB 211 equipped 757's. We could tell when we were dealing with an English controller box because there was usually a puddle of oil on the shelf under it.

[CAPFlyer]

Umm... the only inflight separation of an inlet fan was United Airlines Flight 232 which was a DC-10 with CF6 engines. I met Capt. Haynes on two occasions, and have visited the crash site at Sioux City.

Here's a full list of *all* L1011 accidents and incidents - http://aviation-safety.net/database/dblist.php?Type=336 - Not a single accident due to an engine failure.